This disclosure relates to display devices, such as liquid crystal display (LCD) devices, and more particularly, to a wiring connection technique for display devices that prevents wires in the display regions of display panels from corroding due to corroded test pads disposed outside the display regions.
LCDs constitute one of the more widely used types of flat panel display devices, and typically include an LCD panel for displaying images in response to an external control signal and means for driving the panel. The LCD panel includes upper and lower substrates having a display region and a peripheral region, with a layer of a liquid crystal material sealed between the two substrates. In the manufacture of such LCD panels, thin film transistors, pixel electrodes and the like are formed on the lower substrate, and color filters, a common electrode and the like are formed on the upper substrate. The upper and lower substrates are bonded together, a common seal is formed at their adjacent edges, and the liquid crystal material is then injected between the two substrates to complete the panel.
Completed LCD panels are subject to a visual test after the panel manufacturing process in order to detect signal line defects, such as a short or an open circuit in the signal lines, thin film transistor defects, and the like. The visual test is performed using a plurality of test pads that are located in a peripheral region of the lower substrate and connected to a plurality of signal lines located in the display region of the panel.
After the visual test, the test pads remain exposed to air in the peripheral region of the lower substrate. As a result, the test pads easily corrode. Corrosion generated in the test pads spreads to the signal lines in the display region connected thereto, resulting in corrosion of the signal lines. The corrosion of the signal lines in the display region of the device causes the device to malfunction.